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UNITED STATES PATENT OEEicE,

THOMAS CURRAN, OF NEV YORK, N. Y.

MOLD FOR MAKlNG PLASTER SLABS.

SPECIFICATION' forming part of Letters Patent No. 442,958, datedDecember 16, 1890. Appncaim filed April 8,1890. sereine. 347,077.(roman.)

To all whom' it may concern:

Be it known that I, THOMAS CURRAN, a citizen of the United States,residing in the city, county, and State of New York, have inventedcertain new and useful Improvements in Molds for Making Plaster' Slabs,of which the following is a specification.

The invention relates to an improved molding strip or sheet for formingor molding plastic material, especially that which is adapted to beattached to the interior Walls or ceilings of houses, so that when soattached they will vform a means for the reception of a brown coat and acoat of lhard finish, which are generally applied and employed for suchpurposes.

As stated above, my invention in the pres ent instance relates to theconstruction of the mold, and it relates particularly toimprove ments onthe mold shown, described, and claimed by me in my previous applicationfiled in the United States Patent Office on the 11th day of March, 1890,Serial No. 343,474.

In my previous application I provided a rigid rectangular frame and aflexible molding piece or sheet havin g longitudinal Wooden or otherstrips inserted in the face thereof, and so arranged as to protrude inrelief above the normal surface of the said flexible molding-sheet,whereby when it was applied to a plastic compound contained Within therectangular frame aforesaid, the longitudinal strips would embedthemselves in the plaster and would form corresponding or complementarygrooves therein which were to be utilized for the purpose of retainingthe furn ther and superimposed brown coat and hard finish Well known inthe plasterers art. My present invention is designed to combine therectangular frame with the flexible molding-sheet and to render theWhole structure homogeneous as Well as iiexible, and to this end Iconstruct a mold with its surround ing frame integrally and ofindia-rubber and provide the interior raised portions of ribs similar tothose described and claimed in my previous application aforesaid.

Referring to the accompanying drawings,

which form apart of this specification, Figure I represents across-section of my improved combined fiexible molding sheet and frame,and Fig. II is a plan view thereof.

C represents the longitudinal ribs or raised strips, which extendbetween and connect the ends B B.

D representsthe longitudinal grooves or depressions in the mold, whichare parallel with and intermediate to the longitudinal ribs C. Thesegrooves are provided with corrugation d, as shown in Fig. I, so thatWhen the plaster slab is removed from the mold the outer faces of theslab will have an additional means for supporting the superimposedmortar.

In Fig. I, I show the mold in its operative position, the plasterE beingcontained therein. When the plaster has been inserted in the mold, asshown, it is smoothed over at the surface so that it will be even Withthe frame A A B B. When it has hardened sufficiently the frame and itscontents are turned over.. The frame is then removed from the slab bylifting it at one of its sides A. The mold is so made that by virtue ofits elasticity it can be readily drawn off from the slab in the mannerdescribed. i

Another feature of my invention, and which is set forth in my previousapplication herein referred to, but is applicable also to this, is theformation of the sides or edges of the longitudinal ribs of the flexiblemolding-strip. These sides or edges are preferably made substantially asshown in Fig. I of the accompanying drawings, one of the edges, as shownat F, being considerably inclined after the manner of a dovetail joint,so that when the plaster cast formed thereby is attached to the Wall orceiling the outsetting edge G onthe slab formed by the aforesaidprojection F will retain the mortar and prevent it from dropping. Inother Words, it constitutes a permanent lock for the superimposedplaster or mortar. The opposite sides of the ribs C are made nearlystraight, as shown at H, so that when the mold is Withdrawn it Willencounter no opposition. The corrugations d in the grooves of the moldWill create corresponding elevations and depressions on the IOS mostexposed part of the plaster slab, thereby 2. A mold for forming` plasticslabs with affording` additional support for the mortar dovetailcavities or projections, consisting,` of when applied. the molding-sheetand the surrounding frame x15 Having thus described my invention, the AA B B, made integral with said sheet, and

5 following is what I Claim as new therein and the Whole sheet and framebeing` composed of desire to secure by Letters Patent: I soft rubber,substantially as set forth.

1. A mold for forming plaster slabs with l dovetail cavities andprojections, consisting THOMAS CURRAN. of the molding sheet and framemade integral, izo and the Whole sheet and frame being com- W'itnesses:

posed of soft rubber, substantially as set HERBERT KNIGHT,

forthb l M. V. BIDGooD.

